Merge pull request #73 from MicahChalmer/raw-string-multiline-edit-fix

Fix multi-line raw strings when editing

2 files changed, 56 insertions, 0 deletions

diff --git a/rust-mode-tests.el b/rust-mode-tests.el
index bb40781..b40aed0 100644
--- a/rust-mode-tests.el
+++ b/rust-mode-tests.el
@@ -1067,6 +1067,24 @@ this_is_not_a_string();)"
      "r\" this is a comment\n" font-lock-comment-face
      "\"this is a string\"" font-lock-string-face)))
 
+(ert-deftest font-lock-raw-string-constant ()
+  ;; There was an issue in which a multi-line raw string would be fontified
+  ;; correctly if inserted, but then incorrectly if one of the lines was then
+  ;; edited.  This test replicates how font-lock responds when text in the
+  ;; buffer is modified in order to reproduce it.
+  (with-temp-buffer
+    (rust-mode)
+    (font-lock-fontify-buffer)
+    (insert "const BOO:&str = r#\"\nBOO\"#;")
+    (beginning-of-buffer)
+    (insert " ")
+    (font-lock-after-change-function 1 2 0)
+
+    (should (equal 'font-lock-string-face (get-text-property 19 'face))) ;; Opening "r" of raw string
+    (should (equal 'font-lock-string-face (get-text-property 27 'face))) ;; Closing "#" of raw string
+    (should (equal nil (get-text-property 28 'face))) ;; Semicolon--should not be part of the string
+    ))
+
 (ert-deftest indent-method-chains-no-align ()
   (let ((rust-indent-method-chain nil)) (test-indent
    "
diff --git a/rust-mode.el b/rust-mode.el
index 58df76d..c45d5c1 100644
--- a/rust-mode.el
+++ b/rust-mode.el
@@ -374,6 +374,43 @@
              ("fn" . font-lock-function-name-face)
              ("static" . font-lock-constant-face)))))
 
+(defun rust-extend-region-raw-string ()
+  "Extend the region given by `font-lock-beg' and `font-lock-end'
+  to include the beginning of a string if it includes part of it.
+  Adjusts to include the r[#] of a raw string as well."
+  
+  (let* ((orig-beg font-lock-beg)
+         (orig-end font-lock-end)
+         (beg-ppss (syntax-ppss font-lock-beg))
+         (beg-in-str (nth 3 beg-ppss))
+         (end-ppss (syntax-ppss font-lock-end))
+         (end-in-str (nth 3 end-ppss)))
+    
+    (when (and beg-in-str (> font-lock-beg (nth 8 beg-ppss)))
+      (setq font-lock-beg str-beg)
+      (while (equal ?# (char-before font-lock-beg))
+        (setq font-lock-beg (1- font-lock-beg)))
+      (when (equal ?r (char-before font-lock-beg))
+        (setq font-lock-beg (1- font-lock-beg))))
+    
+    (when end-in-str
+      (save-excursion
+        (goto-char (nth 8 end-ppss))
+        (ignore-errors (forward-sexp))
+        (setq font-lock-end (max font-lock-end (point)))))
+    
+    ;; If we have the beginning of a raw string in the region, make sure we have the end of
+    ;; it.
+    (when (or beg-in-str end-in-str)
+      (save-excursion
+        (goto-char font-lock-beg)
+        (while (and (< (point) font-lock-end) (ignore-errors (rust-look-for-raw-string (buffer-end 1)))))
+        (setq font-lock-end (max font-lock-end (point)))))
+
+    (or (/= font-lock-beg orig-beg)
+        (/= font-lock-end orig-end))
+    ))
+
 (defun rust-look-for-raw-string (bound)
   ;; Find a raw string, but only if it's not in the middle of another string or
   ;; a comment
@@ -702,6 +739,7 @@ This is written mainly to be used as `end-of-defun-function' for Rust."
   (setq-local indent-line-function 'rust-mode-indent-line)
 
   ;; Fonts
+  (add-to-list 'font-lock-extend-region-functions 'rust-extend-region-raw-string)
   (setq-local font-lock-defaults '(rust-mode-font-lock-keywords nil nil nil nil (font-lock-syntactic-keywords . rust-mode-font-lock-syntactic-keywords)))
 
   ;; Misc